<style>
    .container_1 {
        display: flex;
    }

    .container_1 div {
        padding: 10px;
        border: 1px solid silver;
    }

    .box_1 {
        flex: 1;
    }

    .box_2 {
        flex: 3;
    }

    .box_3 {
        flex: 1;
    }
</style>

<div class="container_1">
    <div class="box_1">
        <h3>BOX 1</h3>
        <p>Lorem ipsum dolor sit amet, consectetur
            adipisicing elit. Atque ea facilis praesentium
            quod similique sint vel! Enim minima minus
            non.</p>
    </div>
    <div class="box_2">
        <h3>BOX 2</h3>
        <p>Lorem ipsum dolor sit amet, consectetur
            adipisicing elit. Accusantium aliquam amet
            ducimus, eligendi maiores officiis omnis
            repellendus saepe sapiente vitae!</p>
    </div>
    <div class="box_3">
        <h3>BOX 3</h3>
        <p>Lorem ipsum dolor sit amet, consectetur
            adipisicing elit. Ab asperiores assumenda at ex
            expedita explicabo nihil quos repellat sequi
            totam!</p>
    </div>
</div>
